1. Field of the Invention
The present invention relates generally to stents, stent loading, stent contracting and stent delivery systems and their respective methods of use. Some embodiments of the invention are more specifically directed to stent loading and crimping systems which are configured to minimize cross-contamination.
2. Description of Related Art
A stent is a generally tubular device that is used to support a bodily lumen. A stent is typically delivered to a desired bodily location via a catheter. Often the stent is loaded onto a portion of the catheter, such as a balloon or other region of the catheter shaft. In some stent delivery systems the stent is crimped to the catheter in order to minimize the profile of the stent on the catheter and to prevent undesired movement of the stent relative to the catheter shaft.
A number of techniques for loading and contracting a stent to a catheter shaft or balloon are used. One such technique that is commonly used involves hand crimping the stent to the balloon. A stent is placed over an uninflated balloon and then squeezed with the fingers until the stent is in intimate contact with the uninflated balloon. The technique is highly operator dependent and can affect stent profile and stent placement with respect to the balloon and radiopaque markers. It can also affect the dilatation length of the stent and lead to pinching of the balloon.
Other techniques for crimping stents involve the use of mechanical devices for crimping stents. Mechanical stent crimpers have been disclosed in a number of patents including U.S. Pat. No. 6,387,118; U.S. Pat. No. 6,108,886; U.S. Pat. No. 6,092,273; U.S. Pat. No. 6,082,990; U.S. Pat. No. 6,074,381; U.S. Pat. No. 6,063,102 and U.S. Pat. No. 5,992,000. Mechanical stent crimpers have also been disclosed in a number of copending, commonly assigned patent applications including U.S. application Ser. Nos. 09/401467, 09/401213, 09/404986 and 09/401218. The entire content of each of the above patents and applications is incorporated herein by reference.
In many current stent loading operations particularly those involving self-expanding nitinol or shape memory stents the stent is dipped or sprayed with liquid nitrogen or other cooling agent in order for the stent to achieve a martensitic state. While in the martensitic state the stent is constrained via a crimper or other reducing device. In some cases the crimper comprises an adjustable iris through which the stent is advanced in order to uniformly reduce or compress the stent about its circumference. An example of an iris type stent crimper is described in U.S. Pat. No. 6,360,577, the entire content of which is incorporated herein by reference. Typically, a mandrel or push rod is utilized to drive the stent through the closed iris into a stent delivery mechanism such as a catheter.
Many current stent designs, including balloon expandable, self-expanding and hybrid expandable stents, are configured for the delivery of one or more therapeutic agents or drugs to a location within a body lumen or vessel. In many instances the drug or drugs are carried by the stent in the form of one or more coatings on the stent's surface. Stent loading and/or crimping systems which apply a radially constrictive force directly to the stent through one or more teeth, blades, etc. may adversely affect the drug coating of a stent during the crimping and/or loading process. Furthermore, contact between the crimping blades and the stent may result in some amount of the drug coating being removed from the stent and deposited on the crimping head. This residual amount of drugs may inadvertently be deposited on other stents subsequently crimped resulting in cross-contamination of the stent systems.
In light of the above there is a need to provide stent reducing/loading systems with the capability to reduce the diameter of a stent, particularly a drug coated stent, without direct contact of the stent by the crimping head.
All U.S. patents, applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
Without limiting the scope of the invention a brief summary of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
A brief abstract of the technical disclosure in the specification is provided as well only for the purposes of complying with 37 C.F.R. 1.72. The abstract is not intended to be used for interpreting the scope of the claims.